A brief history of the Polygraph
The modern Polygraph originated from the USA, when in 1921 the Berkeley, California Police Department encouraged Dr. John A. Larson, a psychiatrist, to develop what became the forerunner of the modern-day polygraph. This instrument enabled the first permanent record of blood pressure, pulse, and respiration. This original polygraph was used for many years by the Berkeley Police Department and helped Dr. Larson to correctly distinguish between guilty and innocent suspected criminals.
Later on, Leonard Keeler, a psychologist, became interested in the technique and developed his own instrument to which he added the feature of measuring changes in the skin's resistance to electricity, commonly known as "galvanic skin response."
Keeler is generally recognised as the father of the modern-day polygraph. He combined three important components that are still used today although through modern technology these components are now greatly enhanced. These three things are the pneumograph, cardiograph and the galvanic skin response. Some of the more modern machines have added other electronic devices but Keeler's three main components are still used in the present-day polygraph instrument.
Reference:
www.polygraphexaminer.com
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